@KillianKemps yes, it's called "presence" information, and Conversations chosed not to display it (maybe it can be changed in settings, I'm not sure), but most other clients should be able to display it.
Note that in future, this information should be optional: presence information involve a lot of traffic, and sometimes annoying messages (that's probably why Conversations ignore it).
Under MUC details you can see if people are online though. Usually that’s what I’m interested in — if people are online or not :)